Train detection and control system

ABSTRACT

Control apparatus carried on each train traveling on a nonconducting right-of-way is coupled across a signal transmission channel comprising one propulsion conductor and a sectionalized signal conductor. A wayside signal source transmits a direct current signal, having distinctive predetermined voltage level and polarity characteristics, through each channel section to control train speed and door functions. Each signal conductor section also constitutes one side of a train detection circuit including the signal source and a detector relay. The other side of all detection circuits is established by relay and source connections to a common bus, so that each relay is normally energized. The detector relay shunt circuit is established through the train-carried apparatus to the propulsion conductor and thence its connection to the common bus. Each detector relay thus releases when a train occupies the associated section. Each train detection circuit between stations also includes a front contact of the next advance section detector relay so that station-to-station block occupancy registry is maintained until the train departs from the next station, thus assuring stationto-station train separation.

United States Patent 1 1 1111 3,892,377

Hathaway July 1, 1975 TRAIN DETECTION AND CONTROL [57] ABSTRACT SYSTEM Control apparatus carried on each train traveling on a [75) Inventor: Homer L. Hathaway, Export, Pa. nonconducting right-of-way is coupled across a signal transmission channel comprising one propulsion con- [73] Asslgnee' 3 5 Brake Company ductor and a sectionalized signal conductor. A wayside signal source transmits a direct current signal,

[22] Filed: Oct. 9, 1973 having distinctive predetermined voltage level and polarity characteristics, through each channel section to [2i] Appl' 40475l control train speed and door functions. Each signal conductor section also constitutes one side of a train [52] US. Cl. 246/62; 246/34 R detection circuit including the signal source and a de- [51] Int. Cl. B61] 21/06 tector relay. The other side of all detection circuits is [58] Field of Search 246/34 R, 63 R, 63 C, 73, established by relay and source connections to a com- 246/187 R, 187 B mon bus, so that each relay is normally energized. The

detector relay shunt circuit is established through the [56} References Cited train-carried apparatus to the propulsion conductor UNTED STATES PATENTS and thence its connection to the common bus. Each 2.068.766 1/1937 Reichard 246/34 R deteclor relay releases l" i 'i the 2255797 9/194 Loughridgew 246/62 associated SCll0n. E3Ch tram detectlon circuit be- 2,293,307 3/1942 Place 246/63 C twee" stations also Includes a from wmact 0f the next Primary ExaminerM. Henson Wood, Jr.

Assistant ExaminerReinhard .l. Eisenzopf Attorney, Agent, or Firm-A. G. Williamson, .Ir.; R. W. Mclntire, Jr.

advance section detector relay so that station-tostation block occupancy registry is maintained until the train departs from the next station, thus assuring station-to-station train separation.

9 Claims, 3 Drawing Figures ITR a 3 1 TRAIN DETECTION AND CONTROL SYSTEM BACKGROUND OF THE INVENTION My invention pertains to a train detection and control system. More specifically, this invention relates to a train detection and control arrangement particularly adaptable to personal rapid transit systems.

Personal rapid transit systems (PRT) are becoming more common and are being used to provide small group transportation in relatively restricted areas, normally at low speed around a closed loop right-of-way. They are used. by way of example, in such places as airports between main and auxiliary terminals or gate areas, in large shopping complexes, and on large, sprawling university campuses. They may also-be used in central business districts to provide transportation between terminal stations of more conventional commuter or rapid transit arrangements. These PRT systems are relatively low speed, small vehicle operations, thus allowing simple train detection means and/or separation controls. However, such train detection and speed control arrangements are complicated by the normal use of concrete right-of-ways or guideways on which move rubber tire vehicles. Thus prior art detection and control arrangements which are dependent upon wheelaxle shunts across conductive rails forming the right-ofway cannot be used. Nevertheless, automatic fail-safe detection and train control operation is not only desirable but necessary in such PRT installations from an economic standpoint. Therefore, an efficient and economic arrangement for speed control, including train detection or separation, is required for PRT systems where conventional prior art control methods are not practicable or even possible.

Accordingly, an object of my invention is an automatic train control system for railroads of the transit type.

Another object of my invention is a train detection arrangement for a personal rapid transit system.

Still another object of the invention is an arrangement for detecting the location of, and for maintaining safe separation between, trains or vehicles in a rapid transit transportation system.

A further object of my invention is an arrangement for detection of trains and for controlling the operation thereof in a personal rapid transit system where rubber tire vehicles and a concrete roadway are in use.

It is also an object of the invention to provide a train detection and control system for transit type vehicles using a sectioned signaling rail and one propulsion rail for transmitting wayside detection and control signals.

A further object of my invention is a vehicle control arrangement for PRT systems, where rubber tire vehicles moving on a concrete roadway are in use, comprising a sectionalized signal conductor and a propulsion return conductor to carry vehicle detection and operational control signals having selected voltage and polarity characteristics.

Yet another object of the invention is a control arrangement for a transportation system using a selection of voltage levels and polarities to provide movement or operational control. which signals are transmitted over signal and propulsion conductors of the system in a manner to also provide for train detection and separation.

Other objects, features. and advantages of my invention will become apparent from the following specification when taken in connection with the accompanying drawings and appended claims.

SUMMARY OF THE INVENTION The arrangement embodying my invention is shown applied to a PRT system in which rubber tire vehicles move along a concrete guideway. Propulsion power for the vehicles or trains is picked up from two continuous conductors which parallel the right-of-way. ln practic' ing the invention, the system utilizes an additional sectionalized signal conductor rail together with the propulsion return rail as a channel for transmitting control signals to the vehicles or trains. The train-carried apparatus is connected across this pair of conductors by sliding brushes or pickup shoes in the manner which is conventional to rapid transit operation. Each insulated section of the signal rail or conductor is supplied with a direct current voltage of a predetermined level and polarity. In selecting the level and polarity applied to a particular section, the overall physical characteristics of the right-of-way and the vehicle movement desired is considered. the train-carried apparatus functions to control the speed of the train movement along the right-of-way in accordance with the voltage level and polarity of the received signal. This train-carried apparatus is the specific subject of the disclosure in a co pending application for Letters Patent of the United States Ser. No. 404,766, filed Oct. 9, 1973, by William R. Linderman for a Vehicle Control System and having the same assignee as the present application.

Each section of the signal rail serves as one connection between the d.c. source of selected polarity for that section and the corresponding train detection or track relay. The other side of this track relay circuit is provided by direct connections to a bus wire which is the common for the direct current sources of both polarities. However, the common bus connection also includes or is connected to the propulsion return rail. Thus the train-carried apparatus, comprising various control relays, serves as a shunt around the track relay when the train occupies a particular section. In other words, the train apparatus supplies a connection from the direct current source at the signal rail to the direct current common bus lead bypassing the track relay. A resistor is connected in series with each track relay with sufficient resistance to insure shunting of the relay by the train-carried relays and propulsion return rail. Thus the track relay releases to detect train occupancy of a particular section of the signaling rail in a manner similar to that used in conventional train detection on stan dard railroads. The track relays are selected and so connected as to be provided with proper and sufficient energy for pickup under any level and polarity condition of the direct current signal voltage supplied to that section. Although train detection is accomplished section by section of the signal rail, the arrangement of the invention, because of the nature and characteristics of the vehicles and system operation, is designed for train separation on a station-to-station block basis to assure full safety of operation. This arrangement also includes wayside controls to actuate the opening of the doors on the platforms and to transmit door control signals to the train. An additional means of train presence detection is used at each station platform in order to provide an additional check prior to actuating the opening of the train and platform doors. This is done to insure a complete train stop and the matching of door positions prior to permitting passengers to load and unload from the train vehicles. Additional checks are also con nected into the design of the wayside circuitry so that train departure from a particular station cannot occur until all doors are checked closed and the complete block to the next station in advance is indicated unoccupied by any preceding train or vehicle.

SUMMARY OF THE DRAWINGS Prior to defining the novel features of my invention in the appended claims, I shall describe an arrangement embodying the invention in more specific detail with reference from time to time to the accompanying drawings in which:

FIG. 1 is a diagrammatic illustration of the basic arrangement for train detection and control embodying the invention.

FIG. 2 shows in a diagrammatic manner an expansion of the system of FIG. I to provide one form of stationto-station block separation of the trains.

FIG. 3 is also a diagrammatic circuit illustration of a specific wayside apparatus embodying the invention for detecting trains, for transmitting selected control signals to such trains, and for controlling various other functions along the stretch of right-of-way between and in the vicinity of station platforms.

In each of the figures of the drawings, similar references designate the same or similar parts or apparatus. Standard conventional symbols have been used to designate the apparatus, for example, such as relays and their contacts, push buttons, and/or control circuit lever devices. Further, in FIG. 3, connections to the positive and negative terminals of a local source of direct current operating energy for relays and similar apparatus are designated by the references B and N, respectively. Since the use of such direct current sources for relay operation is conventional and anyone of several types may be employed, a specific local source of such energy is not shown in the drawings.

DETAILED DESCRIPTION OF THE INVENTION I shall now refer to FIG. 1 as a foundation for the following description of the basic arrangement of my invention. In the center of this figure, the dash line block represents a vehicle V having rubber tires which moves from left to right along a concrete or similar type roadway under a positive guidance arrangement. Vehicle V further represents the first or lead vehicle of a train which includes at least two such cars. The right-of-way on which the vehicle moves is outlined to some extent by the parallel single lines, the top one representing a propulsion return rail or conductor and the lower one a sectionalized signal rail or conductor. Each of these conductors or rails extends along the right-of-way either on opposite sides or on the same side depending on the design of the systemv A third such rail which completes the alternating current propulsion power pair is not shown and is not involved in the arrangement of my invention. The signal rail is sectionalized, by insulated joints or air gaps at the joints J, into sections generally designated by the reference T, each with a distinctive prefix, e.g., 2T. It is to be noted that similar separations or insulation of the signal rail into sections in the other drawing figures are designated in the same manner but without any reference I in order to simplify the showings.

The apparatus on the vehicle or train which will be briefly described shortly is coupled to each rail or conductor by a pair of sliding brushes or current pickup shoes. Each pair of brushes is connected by a solid bus lead to which the train-carried apparatus is then connected. Thus the possible loss of contact with the rails by the train-carried apparatus is eliminated or at least reduced to an acceptable low level of occurrence since normally at least one of each pair of brushes will remain in sliding contact with the corresponding conductor. The train-carried apparatus, illustrated for the purpose of completing a description of my invention, comprises four relays and a capacitor connected in multiple between the opposing brush bars. A complete description of the operation of such apparatus is disclosed in the previously mentioned copending application of Linderman. Briefly, each relay is biased, that is, responds only to the specific polarity of voltage which will provide current flowing in the direction indicated by the arrow shown within each relay winding symbol. The relays are also selective as to operation in accordance with the level of the applied voltage. For example, the high speed relay HS and the door open relay DO require the application of a high voltage level in order to receive sufficient energization to operate. This denoted in the drawings by the high voltage symbol HV shown within the winding symbol, Conversely, the medium and low speed relays MS and LS, respectively, as denoted by the low voltage symbol LV within the winding symbol, require only a lower voltage to receive sufficient energization to operate. Obviously, of course, relays MS and LS also operate upon the application of the higher voltage level. In each case, the voltage of course must have proper polarity for a particular relay to operate. A capacitor CV shunting across the bus connections for the pickup brushes bypasses away from the relay windings any alternating current which may be applied due to propulsion current voltage drop in the return rail.

Energy for operation of the train-carried relays and for the wayside track relays is provided by a split signal battery shown at the left of FIG. 1. The extreme positive and negative end terminals of this battery are designated by the references TB and TN, respectively. Where these reference characters appear elsewhere in any of the drawing figures, they designate a connection to the corresponding terminal of the signal battery. The center tap of the signal battery is connected through an inductor L to the propulsion return rail to create normal and reverse polarity sources for the train apparatus through the signal rail. Also connected to this propulsion return rail is a common bus conductor C which is commonly connected through resistors to one side of all track relays. Where the character C appears in other drawing figures, a connection to such a common bus conductor is designated. The double connection to the propulsion return rail is used rather than a direct connection from conductor C to the midpoint of the signal battery to eliminate any unsafe condition which might arise in the event that the connection between the propulsion return rail and the battery center tap becomes open circuited either by a broken connection between the rail and the battery or by an open circuit within inductor L. With the double connection illustrated, any open circuit of this nature will also disconnect the track relays from the common battery terminal and cause them all to release which is a fail-safe action. The full reason will become more clear as the operation of the entire system is explained in the subsequent paragraphs.

Each section of the signal rail conductor has an associated track relay designated by the basic reference character TR with a prefix corresponding to the prefix designating the rail section. Each such track relay is of the biased type and is so connected to respond only to a predetermined polarity applied to that rail section in accordance with the train control needs. Each track relay winding is also shunted by a bypass capacitor which passes around the winding the alternating current which tends to flow in the track circuit due to propulsion current voltage drops as trains pass. The basic energizing circuit for each track relay includes the corresponding section of the signal rail. For example, the circuit for relay lTR extends from terminal TB of the signal battery through a resistor lRL, the IT section of the signal rail, the winding of relay lTR, and a resistor 1R3 to the common bus C and thence through inductor L to the midpoint of the signal battery. A similar circuit is provided for track relay 2TR except that the connection from terminal TB to the rail section 2T is through a resistor 2R2. There are thus three types of resistors used, designated by the basic references R1, R2, and R3. The resistance of these three resistors increases in the numerical order of the suffix and each additional number represents approximately an order of magnitude increase in the total resistance provided. For example, in one specific system, the R1 resistors are on the order of 75 to I00 ohms while the R2 resistors are on the order of 500 to 750 ohms. In this same system, the R3 resistors are on the order of 4,000 to 5,000 ohms in total resistance.

The first two resistors determine the different voltage levels for the train-carried relays while each resistor R3, in direct series with the relay winding, provides sufficient resistance in this circuit path that track relay shunting will be possible through the train-carried relay circuits. As a specific example, in the illustration of FIG. I, track relay 2TR is shunted since vehicle V is occupying the track or rail section 2T. This shunt circuit extends from terminal TB through resistor 2R2, rail section 21', the associated train-carried brushes and the multiple circuit including all train-carried relays to the propulsion return rail, and thence through inductor L to the midpoint of the signal battery. The train-carried relay path is thus a shunt between the connection of the left-hand terminal of relay 2TR to signal rail 2T and the connection from common bus C to the propulsion return rail. Since the series resistance of the winding of relay 2TR and resistor 2R3 is much higher than that of the multiple circuit through the train-carried relays, relay 2TR is effectively shunted and releases. In connection with the track circuits illustrated, it will be noted that relay 3TR is connected with the opposite polarity since battery terminal TN is connected through resistor 3R2 to the rail section 3T. Thus current flow is from right to left through the relay winding or, in other words, from common conductor C through the relay winding, the rail section, and resistor 3R2 to terminal TN.

It is thus obvious that, in the situation illustrated in FIG. 1, although relay 2TR is shunted and released, relays lTR and 3TR are fully energized and picked up. Referring to the train-carried relays, the voltage applied in section 2T is of the proper polarity and voltage level to energize only relays MS since terminal TB is connected to rail section 2T through resistor 2R2 which reduces the voltage level below that required by the high voltage relays such as relay HS. Obviously the flow of current through relay MS is from the brushes coupling to rail section 2T toward the brushes coupling to the propulsion return rail. High speed relay HS would also have been energized when this vehicle occupied section lT since the connection from terminal TB to rail section 1T is through resistor 1R1 which supplies a higher voltage level. When the vehicle moves on into section 3T, the reverse polarity applied to the vehicle relays will be of sufficient level to energize only relay LS. Relay DO would become energized only when the connection from terminal TN to the rail section is through a resistor of the R1 type. It will be noted, therefore, that the train relays are selectively energized in accordance with the occupied track section voltage and polarity. However, normally there is no change in selection in a particular track section since the voltage polarity and level are predetermined during system design. PRT system operation is normally such that a fixed routine of speed operation is possible and desirable and is only conditioned on the separation between the train and the preceding train. As will be developed later, only in the station platform section is the track voltage changed between a door command and a subsequent speed signal command in order to permit the train to leave the station.

Referring now to FIG. 2, I shall discuss one form of arrangement embodying my invention including a stationto-station train separation arrangement. In other words, in the system of FIG. 2, a train cannot depart from station I unless all of the track sections to and including the next station platform have been cleared by the preceding train. This operation is primarily accomplished by specific control circuits provided for track relay lTR which is associated with section 1T adjacent the platform of station 1. With no train occupying the station sections, relay ITR is held energized by a stick circuit arrangement extending from terminal TB through resistor 1R2, from contact a of relay lTR, a from contact of the approach section track relay OTR, section 1T of the signal rail to the winding of relay lTR and through resistor IRS to terminal or conductor C. Track relay OTR and track relays for sections 3T through 8T are illustrated, for the sake of simplicity, only by a single front contact designated by the relay reference. Each of these track relays is controlled by circuit arrangements such as illustrated in FIG. 1 with the voltage level and polarity being predetermined in accordance with the desired speed and operation of trains moving along the stretch of rightof-way. An alternate or pickup circuit for track relay ITR extends from the same terminal TB through resistor 1R2 over a contact closed when the station I sequence has been completed and, in series, from contacts of track relays 8TR, 7TR, 6TR, STR, 4TR and 3TR, and thence through the signal rail section 1T, the winding of relay ITR, and resistor 1R3 to terminal C. Obviously this circuit is interrupted if any one of the track sections 3T through ST is occupied by a train so that the corresponding track relay is released.

As a train approaches station I and occupies section OT, the opening of the front contact of the corresponding track relay OTR interrupts the stick circuit of relay lTR which then also releases. The closing of back contact a of relay lTR prepares a circuit for transmit ting a door open request to the train-carried apparatus. This circuit is completed when the front car of the train, which is the only portion carrying the train apparatus and thus the train shunt. clears section OT so that the front contact of track OTR recloses and the door open request contact also closes. The circuit then is traced from terminal TN of the signal battery through resistor 1R1, the now closed door open request contact, back contact a of relay lTR, and front contact of relay OTR to the signal rail section IT and thence. referring to FIG. 1, through the multiple path of the train-carried apparatus relays. the propulsion return rail, and inductor L to the center point ofthe signal battery. The voltage level and polarity are such that relay D of the train-carried apparatus is energized and actuates the opening of the car doors.

When the station sequence of operations is completed, that is. the various doors have opened and closed, as will be described later, the station sequence complete contact is closed. Meanwhile, the door control contact has opened. The circuit is then complete, providing the preceding train has cleared the track beyond the next station, for applying a proceed signal to the train apparatus of the car occupying section IT. This circuit, of course. is that previously traced from terminal TB through resistor 1R2, the station 1 sequence complete contact now closed, and closed front contacts of all the track relays from section 8T through section 3T to signal rail section IT and thence through the train-carried apparatus to the common terminal of the signal battery as connected to the propulsion return rail. The voltage and polarity characteristics of this applied voltage are such as to energize relay MS shown in FIG. 1 so that the train is authorized to proceed at a medium speed from section 1T. When the train has cleared section lT so that the shunt no longer exists on track relay lTR. this relay then picks up to restore its previously traced stick circuit. It will be noted that the track relay for section 2T is not included in this block check circuit since its contact was included in the check circuit for authorizing the train to depart from the station in approach to station 1 in a manner similar to the inclusion of the front contact of relay 8TR in the just traced checking circuit. It is also to be noted that an alternate departure control including a normally open contact of the manual reset push button is available if the station sequence does not complete properly, or fails to register as completed, so that the corresponding contact does not close in the checking circuit. This manual reset or clearance control is shown sche matically by a dotted line only to illustrate that such controls may be provided for this system.

I shall now turn to FIG. 3 in order to describe a more detailed arrangement of apparatus also embodying my invention and including a second form of station-tostation block, train separation. In this figure, only the sections of the signal rail or conductor are shown with sections AT, BT, CT, and 2ST comprising the stationto-station block. ln other words. the preceding station platform is in the section immediately to the left of rail section AT and the block thus extends to the station platform shown adjacent track section 2ST. Of course, it will be obvious that additional track sections may be included between the stations if additional controls or length of track stretch makes it desirable or necessary. The circuits for the track relays are similar to those shown in FlG. 1 except that, for the sections between stations, each includes a front contact of the advance section track relay. The circuits for the track relay of the station section 2ST provide for selection of different voltages and polarities in order to accomplish the necessary controls on the trains occupying that area.

Tracing the circuit for track relay ATR, it extends from terminal TB over front contact a of track relay BTR. resistor AR], section AT of the signal rail, resistor AR3, and the winding of relay ATR to terminal C. Since an R1 type resistor is used in series with the connection from terminal TB, the voltage level and polarity are such as to permit the highest train speed for any train occupying this particular section. In other words, in the basic system shown in FIG. 1, the high speed relay HS on the train would be energized, The circuit for relay BTR includes front contact a of track relay CTR of the advance section, while the circuit for relay CTR includes front contact a of track relay ZSTR of the advance or station platform section. It will be further noted that the circuit for applying energy from terminal TB to section BT includes a type R2 resistor so that a medium speed is authorized in this seciton. The section CT connection from terminal TN includes another R2 type resistor so that, with reverse polarity and low voltage, a low speed is authorized for trains moving through this section. It will be obvious from the arrangement that, subsequent to the passage of a train through this stretch of right-of-way, the track relays will pick up in the reverse sequence, beginning with track relay 2STR and continuing to the left so that relay ATR will be the final one to be reenergized. Thus a station-to-station train separation or block check is provided, as will be described in more detail shortly.

The circuit which normally holds track relay 2STR energized includes front contact I) of relay CTR, resistor 2SR2, section 2ST of the signal rail, and resistor 2SR3. Obviously this circuit cannot function as a pickup circuit for track relay ZSTR since relay CTR releases when an approaching train occupies section CT and can only be reenergized after relay ZSTR picks up. Thus an alternate circuit for energizing relay 2ST upon the departure the train extends from terminal TB over from contact b of the station gate open relay 2560 and thence over the resistors and signal rail section previously described to the winding of relay ZSTR and terminal C. A second or alternate circuit for reenergizing relay ZSTR includes front contact a of the block reset relay BR and a resistor R4 and thence over the previously traced circuit including resistors and rail section to the relay winding. Relay BR is controlled by a simple circuit including a normally open contact of a reset push button RPB which, when manually operated, closes a circuit for energizing the relay which remains energized only as long as the push button is actuated. This action will be taken by the system controller if, for some reason, the usual clearing operation for the station-to-station block does not function as intended. Resistor R4 is added in this alternate pickup circuit in order to further reduce the voltage applied to section 2ST to a level which only reenergizes the associated track relay and which is not sufficient to cause the op eration of any of the train-carried relays. Thus, The clearing of the block or the inadvertent operation of the push button while the train is occupying this section cannot actuate or command the train to proceed when conditions are otherwise not proper. The final circuit for supplying energy to section 2ST which involves the operation of the platform and car doors will be discussed shortly.

In the lower right of FIG. 3, within the dot-dash rectangle, are three contacts which are associated with the station platform shown adjacent section 2ST. The upper of these contacts is closed when the presence of a train stopped at the station platform is detected. Such control may be exercised magnetically, e.g., a reed relay, with energy supplied to the train carried magnet only when the train has stopped, that is, when the train has zero velocity. The other two contacts are separately closed when doors along the platform which match the location of the train doors are opened or closed, respectively. Such contacts could be controlled by limit switches reflecting the position of the actual platform doors. Since no train is occupying the station platform area, obviously the platform doors closed detectors have closed the corresponding contact, that is, the lower contact, while the doors open contact is released. The train presence detector contact, through a simple and obvious circuit, controls the train presence detector relay TPD, which in energized and picked up when the contact is closed. A similar simple circuit is provided by which the platform doors closed detector contact controls the energization of the doors closed indication relay DC], the relay being energized when the doors are detected in their closed position. The final relay associated with these contacts, the doors open indication relay DOl, is energized by a circuit including the doors open detector contact and front contact a of the open door control relay ODC. Relay D] is of the time element type so that, after being energized, it does not pick up and close front contacts for a predetermined time period which may be on the order of l5 to 60 seconds or even longer if such requirements exist. The slow action of this relay is conventionally indicated by the upward pointing arrows drawn through the movable portion of each of its contacts. Once picked up, relay D01 is held energized by a stick circuit which includes back contact 6 of track relay CTR and front contact a and the winding of relay DO].

In addition to relays ODC and ZSGO already mentioned, there are associated with this station 2 area the close door control relay CDC, the station stop control lever SSCL, and a rear clear check relay lRCC. This last relay is so numbered because it enters into the control for the release of trains from the preceding station 1 to the left of FIG. 3. The front contact b of a corresponding relay ZRCC is shown in one of the circuits. The control or energization circuit for relay ZRCC is similar to that shown for relay lRCC but involves contacts of relays associated with the next station in advance, that is, station 3. The operation of this front contact of relay 2RCC will be clear when the operation of relay lRCC is subsequently described.

Returning now to the circuit for relay ODC, it can be seen that it includes back contact a of relay ZSGO, front contact a of relay TPD, and back contact a of relay CDC. Thus relay ODC is energized when the presence of a stopped train is detected at the station platform but only if the gate has not been opened to release the train and no close door command is in effect. The normal energizing circuit for relay CDC extends from terminal B at front contact a of relay ZATR over front contact 11 of relay 2RCC, the circuit arm of lever SSCL in its A position, and front contact b of relay DOl through the winding of relay CDC to terminal N of the local source. Front contact I) of relay D0] in this circuit may be bypassed by moving lever SSCL to its P or station pass position. The three positions of this lever include the normal A or automatic position, the P or station pass position selected if the station is to be bypassed by a train as far as loading of passengers is concerned, and the hold position H selected when a train is to be held at the station. This is accomplished by prohibiting the closing of the platform doors when the lever occupies its H position, since the circuit for relay CDC is interrupted.

Relays ODC and CDC exercise control over the previously mentioned platform doors by circuits which originate from the dot-dash rectangle in the form of a door control signal output on the bottom line from the block. This signal is returned as an open door command over front-contact h of relay ODC when this relay is energized. When relay CDC is picked up, the circuit for closing the doors extends from the same output signal lead over front contact b of relay CDC to the close door operating mechanisms. It is believed that this sim ple schematic showing of the platform door control is sufficient for an understanding of the operation of this portion of applicants inventive arrangement.

The energizing circuit for relay 2560 also includes front contact a of relay ZATR and from contact b of relay 2RCC and then extends over from contact a of relay DCI, from contact c of relay CDC, and back contact a of relay ATR to the winding of relay 2500. Back contact a of relay ATR may be replaced in this circuit by a back contact of relay BTR if desirable or more suitable in contact requirements. When relay 2SGO picks up, the closing of its front contact a completes a stick circuit which further includes back contact a of relay ATR. It will be noted that the winding of relay 2860 is shunted by a resistor-capacitor network which provides a slight delay to the release of this relay to bridge momentary circuit interruptions between the completion of the stick circuit and the opening of the pickup circuit. This slight delay in release is necessary since the opening of back contacts of relay 2860 will deenergize relay ZRCC whose front contact b is in the normal energizing circuit for relay 2500. This can be understood from the following description of the control of relay lRCC which is similar in nature. The energizing circuit for relay lRCC includes back contact a of relay 2ATR which closes as the train departs from the station and front contact c of relay ZSGO. When relay lRCC picks up, the closing of its front contact a completes a stick circuit which further includes back contact e of relay lSGO associated with the station 1 area in the manner equivalent to that just described for relay ZSGO. Obviously then, relay ZRCC, of which only the single front contact b is shown, will be energized in a similar manner as a preceding train leaves the station 3 platform and will then remain energized until relay ZSGO picks up to permit the departure of a subsequent train from station 2 platform.

I shall now describe the operation of the apparatus based on the arrangement shown in FIG. 3. It is as sumed initially that no train occupies any portion of the stretch shown. With the right-of-way thus unoccupied, all track relays are picked up as shown in the drawing. All the relays shown are in a released position except for relay DCI which, as shown, is energized and picked up, It is further assumed that lever SSCL is in its A position. Front contact b of relay 2RCC is shown closed, it being assumed that the preceding train has cleared the next station and, since relay 2800 is released, the stick circuit is in effect. Relay lRCC is shown released since it is assumed that the train is ready to leave the preceding station and therefore relay ISGO has picked up to deenergrze relay lRCC.

As the approaching train enters section AT, it shunts track relay ATR which releases. The traincarried ap paratus receives a high voltage, positive polarity signal so that the highest speed allowed in this system is in effeet, As the train continues and enters section BT, relay BTR releases. The opening of front contact a of this latter relay opens the circuit for relay ATR so that this relay is held released and the application of any speed signal to section AT is interrupted. The train receives a low voltage, positive polarity signal while in section BT so that the medium speed is in effect. In a similar manner, relay CTR releases as the train occupies section CT and the opening of its front contact a interrupts the circuit for relay BTR and for applying any speed signal to section ET. The train receives a reverse polarity, low voltage signal while in section CT so that the lowest authorized speed is in efiect for the train operation. Since section CT, the station approach, is normally shorter than other sections, the low speed limit is effective principally to prepare for a station stop. The opening of front contact b of relay CTR also interrupts the supply of energy to track section 2ST so that relay ZSTR releases at this time. As the train enters section 2ST, no speed signal is received and the train executes a stop at the station platform. The release of relay ZSTR, at its front contact a, interrupts the track circuit supply for section CT and relay CTR cannot now pick up when the train clears that section. It is to be remembered that relays BTR and ATR also cannot pick up until the entire block is cleared. that is, until the train has left station 2.

When the train has stopped at the station platform, the presence detector contact closes and relay TPD is energized and picks up. The closing of front contact a of relay TPD completes the circuit for relay ODC and this latter relay picks up, closing its front contact 12 to actuate the opening of the platform doors. Front contact c of relay ODC completes the circuit from terminal TN, further including hack contacts a of relays CDC and 2860, for supplying reverse polarity energy to the signal rail in section 2ST. Since this circuit in cludes resistor ZSRl, a high voltage, reverse polarity signal is applied and actuates the train-carried apparatus through the energization of relay D to open the car doors. With the platform doors open, relay DCl is released. The closing of the doors open detector contact completes the circuit, since front contact a of relay ODC is already closed, for energizing relay DOI and this relay begins its timing period. At this point then, the train has stopped at the platform, both car and platform doors are open, and passengers may load and unload as they desire.

When relay DOl picks up at the end of its timing pe riod, the closing of its front contact h completes the previously traced circuit for energizing relay CDC since circuit control lever SSCL is in its A position It may be noted at this point that, if the station stop pe' riod for this train was to be shortened or eliminated altogether, lever SSCL would have been placed in its station pass position P by the system operator at the time that the train was arriving or prior thereto. This would initiate at once, bypassing the relay DOI timing period, the following actions which are discussed for controlling the train departure. When relay CDC picks up, its back contact a opens the circuit for relay ODC which releases to remove the open door signal from section 2ST. Relay CDC also opens this signaling circuit at its back contact d. This causes the car doors to close. The closing of front contact b of relay CDC actuates the closing of the platform doors, especially since front contact I) of relay ODC is now open. Relay DC] is energized when the detector contact closes upon the completion of the door closing operation at the platform. The closing of front contact a of relay DCl finally completes the circuit for energizing relay ZSGO since all other contacts in this circuit are previously closed, especially front contact c of relay CDC and back contact a of relay ATR. Relay ZSGO, thus energized, picks up and sticks over back contact a of relay ATR upon the closing of its own front contact a.

When relay ZSGO picks up to open its back contact d, it further interrupts the circuit for applying the reverse polarity, high voltage signal to rail section 2ST. This is a safety check to insure that no manual action can subsequently cause the car doors to be opened. Front contact b of relay ZSGO closes to apply a low voltage, positive polarity signal to rail section 2ST so that the train relays are actuated to cause the train to advance or leave the station at a medium speed rate. Relay ZSTR of course is shunted and cannot therefore pick up until the train actually clears the track section. As the train enters section ZAT upon leaving, relay ZATR releases, opening its from contact a to deenergize relay CDC which then also releases. However, the platform doors remain closed in the absence of any opposite or open command. Relay ZSGO of course is now held only by its stick circuit. The closing of back contact a of relay ZATR, with front contact c of relay ZSGO already closed, completes a circuit for energizing relay lRCC. This relay picks up, completing its stick circuit which further includes back contact e or relay ISGO associated with station 1. This prepares the circuits associated with this rear station for permitting a train to depart therefrom when relay ATR has picked When this train clears section 2ST, relay ZSTR is energized by the low voltage, positive polarity signal originating at front contact b of relay 2560 and relay ZSTR picks up. Since the block from the preceding station is clear, relays CTR, BTR, and ATR are picked up in this order following the closing of front contact a of relay ZSTR. The opening of back contact a of relay ATR interrupts the stick circuit for relay 2860 which releases. Thus the apparatus illustrated in FIG. 3 is, at this point, returned to normal. If for some reason the various track relays fail to pick up, that is, the block does not clear out, the operation by the system operator of push buttoned RPB to pick up relay BR will apply sufficient energy to section 2ST to pick up relay 2STR to initiate a block reset in this manner. As previously mentioned, the level of this signal is insufficient to transmit a signal to any train to cause it to register an advance or proceed command. Similar reset circuits may be used to energize the various RCC relays under similar or equivalent conditions.

Reviewing briefly, the train is thus advanced through the stretch of right-of-way shown and, upon entry into section 2ST, automatically stops at the station platform due to the operation of the track relay arrangement which previously removed the speed signal from the platform track section. The detection of the presence of the train stopped at the platform initiates the door opening sequence during which both train and platform doors are opened to allow passengers to enter and leave the train. Following a predetermined timing period established by relay DOI, the doors on both train and platform are closed and a gating relay 2860 is energized to initiate the departure operation. The application of a medium speed signal at this time, when the doors have been closed and checked in that position, causes the train to leave the platform at this medium speed. When the train occupies the departure section in advance, the section ZAT, the reset of the apparatus is initiated and is carried out in an automatic manner. Station-to-station blocks are accomplished through the track relay arrangement which detects a train in each succeeding track section but which cannot clear until the train has cleared the final station rail section. The clearing of the approach stretch to any platform is also checked and a control registered which permits the following train to depart from the station in approach.

The arrangement of my invention thus provides a safe and efficient train control for a transportation system in which conventional train detection is not possible, specifically for PRT type transportation. In other words, the system provides a safe and efficient control operation where the trains or vehicles move over con crete roadway on rubber tires so that other detection methods are impractical. The trains are permitted to move at the allowable speeds between stations under a continuous detection that allows a safe separation to be maintained between following trains. This operation is accomplished with a minimum amount of apparatus relative to the problems of detecting and signaling to vehicles which are insulated from the roadway and from normal detection arrangements. A safe, efficient, and economical control system is thus provided for personal rapid transit arrangements which move people quickly and comfortably about a restricted area between relatively closely related positions.

Although l have herein shown and described but a single basic arrangement for detecting trains and maintaining their separation in a system which prevents normal detection arrangements, it is to be understood that various changes and modifications therein within the scope of the appended claims may be made without departing from the spirit and scope of my invention.

Having now described the invention what I claim as new and desire to secure by Letters Patent is:

1. A vehicle detection system, for a transportation system in which the vehicles move on a fixed right-ofway, comprising in combination,

a. a communication channel including a pair of conductors extending along said right-of-way and including,

l. a signal conductor divided into insulated sec tions of predetermined length to establish chan nel sections corresponding to selected sections of said right-of-way, and

2. another conductor being continuous and connected to a common bus,

b. a signal source coupled between each signal conductor section and said common bus for transmit ting through each channel section a signal having a predetermined characteristic,

c. control apparatus on each vehicle coupled across said conductors for receiving the signal transmitted in each channel section, and,

d. a wayside detection means for each section operable between first and second conditions and connected between the corresponding signal conductor section and said common bus for normally receiving the signal transmitted through that section and responsive thereto for operating to said first condition to indicate the nonoccupied condition of the corresponding right-of-way section,

c. said control apparatus on each vehicle further effective to shunt the signal transmitted through a signal conductor section away from the associated detection means into said common bus when that vehicle occupies the corresponding right-of-way section,

1. the associated detection means responsive to said signal shunt for operating to its second con dition to indicate the occupancy of that right-ofway section by that vehicle.

2. A vehicle detection system as defined in claim 1 in which,

a. the transmitted signals are direct current voltages having predetermined level and polarity characteristics, and

b. the detection means for each section is coupled to respond to the distinct polarity and any voltage level of the direct current signal transmitted through the associated signal conductor section.

3. A vehicle detection system as defined in claim 2 in which said right-of-way is further divided into station to station blocks each comprising a plurality of sections and in which,

a. each wayside detection means for a section between stations is further controlled by the detection means of the adjacent advance section for inhibiting response of each between stations detection means to a nonoccupied condition of the corresponding section while the last occupying vehicle still occupies any section to and including the next advance station section,

b. the wayside detection means for each station sec tion is further controlled normally by the approach section detection means for providing approach detection of an approaching vehicle and for interlocking each station section detection means and the associated approach section detection means in their second conditions to retain an occupancy indication once detected until after that vehicle departs from the station section, and which further includes,

c. a station gate means controlled by the advance station to station block occupancy conditions and by selected wayside conditions at the associated station for connecting said signal source to the signal conductor for that station section only when that vehicle is authorized to depart from that station to provide reset energy for said station section detection means which overrides said interlocked condition.

4. A vehicle detection system as defined in claim 2 in which,

a. each wayside detection means is a biased direct current detector relay,

b. said signal source is a direct current energy source having end terminals of preset different polarities and a midpoint terminal connected to said common bus,

c. a selected end terminal of said source is connected to each signal conductor section in accordance with the predetermined characteristics of the signal to be transmitted through that section,

d. the winding terminals of each detector relay are selectively connected to the associated signal conductor section and said common bus to supply energy of proper polarity for operating the relay to detect the nonoccupied condition of the corresponding right-ofway section, and

e. each vehicle control apparatus is distinctly respon sive to the polarity and voltage level of each re ceived signal for selectively controlling vehicle speed and other functions.

5. A vehicle detection system as defined in claim 4 in which, station platforms are located adjacent selected signal conductor sections, and also in which,

a. the source connection to each signal conductor section between stations includes an energized position contact of the detector relay associated with the next signal conductor section in advance in direction of vehicle movement, and

b. the source connection for each signal conductor station section comprises a first path including an energized position contact of the detector relay as sociated with the station approach signal conductor section and a second path including a normally open contact closed when a vehicle is authorized to depart from that station 6. A train detection system for a transit system in which the trains move on a nonconducting right-ofiway on insulated wheels, comprising in combination,

a. a signal transmission channel along said right-ofway including a first and a second conductor,

1. said first conductor electrically separated into sections of predetermined lengths corresponding to selected sections of said right of-way b. a signal source connected between each first conductor section and a common bus for transmitting a signal having a preselected characteristic through each first conductor section,

c. a train detection means for each section coupled between the corresponding first conductor section and said common bus for normally receiving the transmitted signal and responsive thereto for indi cating the nonoccupied condition of the corre sponding section of said right-of-way, and

d. a shunt circuit means on each train coupled between said first and second conductors,

e. said second conductor also connected to said common bus for completing a shunt path bypassing the transmitted signal from a particular train detection means when a train occupies the corresponding section of right-of-way,

1. each train detection means responsive to the absence of any received signal for indicating the occupancy of the corresponding section of said right-of-way by a train,

7. A train detection system as defined in claim 6 in which.

a. each train detection means comprises a detector relay with one winding terminal connected to said common bus,

b. the other winding terminal of each detector relay connected to one end of the associated first conductor section,

c. said source being connected to the other end of each first conductor section in a manner to transmit the signal with the preselected characteristic through that section,

d. said one and other terminals of each relay winding selected to provide response by the relay to the re ceived signal when the corresponding section of said right-of-way is unoccupied by any train.

8. A train detection system as defined in claim 7 in which,

a. each detector relay is biased direct current relay,

b. said signal source is a direct current energy source having end terminals of preset different polarity and a midpoint terminal connected to said common bus,

c. a selected end terminal of said source connected to said other end of each first conductor section in accordance with the desired characteristics of the signal transmitted through that section,

d. said one and other winding terminals of each detector relay selectively connected to the associated first conductor section and said common bus for energizing that relay with proper polarity energy to operate under section nonoccupied conditions.

9. A train detection system as defined in claim 8, and having station platforms located adjacent selected sections, in which,

a. the energy source connection to each first conductor section between station platforms includes an energized position contact of the detector relay associated with the adjacent advance section, and

b. the energy source connection to each first conductor station section comprises, in multiple,

l. a first path including an energized position contact of the detector relay associated with the station approach section, and

2. a second path including a normally open contact closed when a train is departing from the corresponding station. 

1. A vehicle detection system, for a transportation system in which the vehicles move on a fixed right-of-way, comprising in combination, a. a communication channel including a pair of conductors extending along said right-of-way and including,
 1. a signal conductor divided into insulated sections of predetermined length to establish channel sections corresponding to selected sections of said right-of-way, and
 2. another conductor being continuous and connected to a common bus, b. a signal source coupled between each signal conductor section and said common bus for transmitting through each channel section a signal having a predetermined characteristic, c. control apparatus on each vehicle coupled across said conductors for receiving the signal transmitted in each channel section, and d. a wayside detection means for each section operable between first and second conditions and connected between the corresponding signal conductor section and said common bus for normally receiving the signal transmitted through that section and responsive thereto for operating to said first condition to indicate the nonoccupied condition of the corresponding rightof-way section, e. said control apparatus on each vehicle further effective to shunt the signal transmitted through a signal conductor section away from the associated detection means into said common bus when that vehicle occupies the corresponding right-of-way section,
 1. the associated detection means responsive to said signal shunt for operating to its second condition to indicate the occupancy of that right-of-way section by that vehicle.
 2. A vehicle detection system as defined in claim 1 in which, a. the transmitted signals are direct current voltages having predetermined level and polarity characteristics, and b. the detection means for each section is coupled to respond to the distinct polarity and any voltage level of the direct current signal transmitted through the associated signal conductor section.
 2. another conductor being continuous and connected to a common bus, b. a signal source coupled between each signal conductor section and said common bus for transmitting through each channel section a signal having a predetermined characteristic, c. control apparatus on each vehicle coupled across said conductors for receiving the signal transmitted in each channel section, and d. a wayside detection means for each section operable between first and second conditions and connected between the corresponding signal conductor section and said common bus for normally receiving the signal transmitted through that section and responsive thereto for operating to said first condition to indicate the nonoccupied condition of the corresponding right-of-way section, e. said control apparatus on each vehicle further effective to shunt the signal transmitted through a signal conductor section away from the associated detection means into said common bus when that vehicle occupies the corresponding right-of-way section,
 2. a second path including a normally open contact closed when a train is departing from the corresponding station.
 3. A vehicle detection system as defined in claim 2 in which said right-of-way is further divided into station to station blocks each comprising a plurality of sections and in which, a. each wayside detection means for a section between stations is further controlled by the detection means of the adjacent advance section for inhibiting response of each between stations detection means to a nonoccupied condition of the corresponding section while the last occupying vehicle still occupies any section to and including the next advance station section, b. the wayside detection means for each station section is further controlled normally by the approach section detection means for providing approach detection of an approaching vehicle and for interlocking each station section detection means and the associated approach section detection means in their second conditions to retain an occupancy indication once detected until after that vehicle departs from the station section, and which further includes, c. a station gate means controlled by the advance station to station block occupancy conditions and by selected wayside conditions at the associated station for connecting said signal source to the signal conductor for that station section only when that vehicle is authorized to depart from that station to provide reset energy for said station section detection means which overrides said interlocked condition.
 4. A vehicle detection system as defined in claim 2 in which, a. each wayside detection means is a biased direct current detector relay, b. said signal source is a direct current energy source having end terminals of preset different polarities and a midpoint terminal connected to said common bus, c. a selected end terminal of said source iS connected to each signal conductor section in accordance with the predetermined characteristics of the signal to be transmitted through that section, d. the winding terminals of each detector relay are selectively connected to the associated signal conductor section and said common bus to supply energy of proper polarity for operating the relay to detect the nonoccupied condition of the corresponding right-of-way section, and e. each vehicle control apparatus is distinctly responsive to the polarity and voltage level of each received signal for selectively controlling vehicle speed and other functions.
 5. A vehicle detection system as defined in claim 4 in which, station platforms are located adjacent selected signal conductor sections, and also in which, a. the source connection to each signal conductor section between stations includes an energized position contact of the detector relay associated with the next signal conductor section in advance in direction of vehicle movement, and b. the source connection for each signal conductor station section comprises a first path including an energized position contact of the detector relay associated with the station approach signal conductor section and a second path including a normally open contact closed when a vehicle is authorized to depart from that station.
 6. A train detection system for a transit system in which the trains move on a nonconducting right-of-way on insulated wheels, comprising in combination, a. a signal transmission channel along said right-of-way including a first and a second conductor,
 7. A train detection system as defined in claim 6 in which, a. each train detection means comprises a detector relay with one winding terminal connected to said common bus, b. the other winding terminal of each detector relay connected to one end of the associated first conductor section, c. said source being connected to the other end of each first conductor section in a manner to transmit the signal with the preselected characteristic through that section, d. said one and other terminals of each relay winding selected to provide response by the relay to the received signal when the corresponding section of said right-of-way is unoccupied by any train.
 8. A train detection system as defined in claim 7 in which, a. each detector relay is biased direct current relay, b. said signal source is a direct current energy source having end terminals of preset different polarity and a midpoint terminal connected to said common bus, c. a selected end terminal of said source connected to said other end of each first conductor section in accordance with the desired characteristics of the signal transmitted through that section, d. said one and other winding terminals of each detector relay selectively connected to the associated first condUctor section and said common bus for energizing that relay with proper polarity energy to operate under section nonoccupied conditions.
 9. A train detection system as defined in claim 8, and having station platforms located adjacent selected sections, in which, a. the energy source connection to each first conductor section between station platforms includes an energized position contact of the detector relay associated with the adjacent advance section, and b. the energy source connection to each first conductor station section comprises, in multiple, 